Abstract: A glycoprotein isolated from Aloe, a plant belonging to Liliaceae, having a molecular weight of 1.8.times.10.sup.4 and a ratio of protein to sugar of 8 to 2 by weight; yielding only a single band upon SDS-polyacrylamide gel electrophoresis without 2-mercaptoethanol treatment and yielding two discrete bands upon SDS-polyacrylamide gel electrophoresis with 2-mercaptoethanol treatment; having hemagglutinating and cytoagglutinating activity for transformed cells; having mitogenic activity for lymphocytes, cap forming activity for lymphocytes and cultured transformed cells using fluorescence labeled glycoprotein; having binding reactivity with some types of serum proteins; and having the capability of activating complement components.